In locomotive consists where the locomotives are powered by natural gas, there is a need to determine the positional relationships between the locomotives and a tender car carrying the natural gas. When transporting natural gas, the most efficient means is to transport it in a liquid state. Liquefied natural gas (“LNG”) takes up only a fraction (about 1/600) of the volume of natural gas in its gaseous state, and may be maintained in its liquid state in cryogenic compartments. LNG is stored in cryogenic compartments either at or slightly above atmospheric pressure. To produce LNG, natural gas is cooled below its boiling point (about −161° C. at ambient pressure). While it is practical to transport LNG because it takes up a fraction of the volume of natural gas in its gaseous state, natural gas is usually required in its gaseous state for combustion. LNG may be converted into its gaseous form by raising the temperature of the LNG. There are advantages to transporting the natural gas in liquid form, and a desire to reduce the distance over which the natural gas must be piped in its gaseous state to reach the engines on the locomotives. As a result, there is a desire to provide a tender car as part of the locomotive consist.
A tender car provided as part of a locomotive consist will need to receive communications from the locomotives in the consist related to the individual fuel requirements of each locomotive. The positional relationships between the locomotives and the tender car may need to be determined. Information on the positional relationships between cars in a consist may be used to identify which locomotive a particular fuel requirement is coming from, and which end of the tender car the fuel should be supplied from.
One attempt at determining the positional order of the various cars in a train is described in U.S. Pat. No. 4,689,602 (Morihara et al.), which describes a system including a selecting relay that applies an input signal to one of plural data transmitting devices, one being located on each car of the train. Each of the data transmitting devices are connected through extension lines to a single, common line. Logic circuits are provided for the extension lines to supply, in response to an output signal from the respective data transmitting devices, a supply voltage to the following data transmitting device. In the case of a train with more than two cars, the front car must be selected first, and then the data transmitting devices on each of the remaining cars are started in succession, with the position of each car being registered at the data transmitting device on the front car.
Although the system disclosed by Morihara et al. may improve the ability to detect the various positions of cars in a train, the system requires the initial selection of a front car. Data must then be transmitted from successive data transmission devices along the train back to the front car in order to register the proper positional relationships between the cars. The system disclosed by Morihara et al. does not provide a way for a tender car controller connected by a common communication link with plural locomotives to distinguish between the locomotives. The system disclosed by Morihara et al. also does not provide a way for each of the locomotives connected to a tender car to identify which end of the tender car the locomotive is connected to.
The disclosed system and method is directed to overcoming one or more of the problems set forth above and/or elsewhere in the prior art.